Chennai, Feb. 5: Air Traffic Control (ATC) at Chennai airport today complained of “operational problems” following the second intrusion by an unidentified aircraft into Indian airspace in the last five days.

Official sources here said they “cannot identify the aircraft” but suspect that on both occasions it was a US Air Force plane. Chennai ATC failed to establish radio contact with a second “mystery flight” yesterday even though a “blip movement” appeared and lasted for nearly two hours on their radar.

In a near-repeat of the January 31 incident, the “mystery plane” yesterday did not respond to any of the radio channel frequencies, the sources said, adding that the aircraft was flying 150 to 160 miles east of Chennai.

On January 31, an “unidentified aircraft”, said to be a US air force Boeing 707, breached Indian airspace about 170 nautical miles east of the city airport.

After the incident, a team of top civil aviation, home ministry and air force officials rushed to Chennai for a spot inquiry into the aircraft overflying without prior permission.

The ATC has taken up yesterday’s matter with the Directorate General of Civil Aviation.

A foreign aircraft was grounded in Mumbai on Monday after it entered Indian airspace without permission.

ATC sources said it was up to the DGCA to take further action. “Movements (by any foreign plane) within our airspace should be coordinated, but that is not happening,” the sources added.

In a related incident, the Communist Party of India today urged Prime Minister Atal Bihari Vajpayee to take up the matter with the US authorities immediately. “This is a matter of serious concern for Indian security,” said CPI national secretary D. Raja. “The Vajpayee government should raise the issue with the US of violating our air space every now and then.”

Raja, who was here from New Delhi in connection with a party meeting, told reporters this was not the first time that the US was flouting “all International norms and laws in this regard”. He recalled how a helicopter from the US Seventh Fleet last year made sorties over the Kalpakkam nuclear power plant without permission from the ATC. This smacked of the “US attitude of arrogance,” Raja said.